I've bought most of my current fish from petsmart (except for my Uara, Nicaragua, Lima Shovelnose Cat, Cuban, Texas) and I have to say my Petsmart is not that bad. It's all young girls that work there, most do not know much but like someone else said they don't act like they do. I mostly go there these days for foods or filter media but I always end up browsing there tanks, which are seem to be kept up with well.
With that said, If someone is blatantly rude to you asking you ignorant questions that have no merit, they deserve to lose there job. Most of us adults have been there, worked through our cruddy youth jobs for some quick cash and/or build up your resume. If you don't like your job (join the club), either suck it up and do it well hoping to move up or find another job, it IS as simple as that. I personally think the kid should loose his job, maybe it will be a minor wake up call.